// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_PROXY_PROXY_CONFIG_SERVICE_LINUX_H_
#define NET_PROXY_PROXY_CONFIG_SERVICE_LINUX_H_

#include <stddef.h>

#include <memory>
#include <string>
#include <vector>

#include "base/compiler_specific.h"
#include "base/environment.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/observer_list.h"
#include "net/base/net_export.h"
#include "net/proxy/proxy_config.h"
#include "net/proxy/proxy_config_service.h"
#include "net/proxy/proxy_server.h"

namespace base {
class SingleThreadTaskRunner;
} // namespace base

namespace net {

// Implementation of ProxyConfigService that retrieves the system proxy
// settings from environment variables, gconf, gsettings, or kioslaverc (KDE).
class NET_EXPORT_PRIVATE ProxyConfigServiceLinux : public ProxyConfigService {
public:
    class Delegate;

    class SettingGetter {
    public:
        // Buffer size used in some implementations of this class when reading
        // files. Defined here so unit tests can construct worst-case inputs.
        static const size_t BUFFER_SIZE = 512;

        SettingGetter() { }
        virtual ~SettingGetter() { }

        // Initializes the class: obtains a gconf/gsettings client, or simulates
        // one, in the concrete implementations. Returns true on success. Must be
        // called before using other methods, and should be called on the thread
        // running the glib main loop.
        // One of |glib_task_runner| and |file_task_runner| will be
        // used for gconf/gsettings calls or reading necessary files, depending on
        // the implementation.
        virtual bool Init(
            const scoped_refptr<base::SingleThreadTaskRunner>& glib_task_runner,
            const scoped_refptr<base::SingleThreadTaskRunner>&
                file_task_runner)
            = 0;

        // Releases the gconf/gsettings client, which clears cached directories and
        // stops notifications.
        virtual void ShutDown() = 0;

        // Requests notification of gconf/gsettings changes for proxy
        // settings. Returns true on success.
        virtual bool SetUpNotifications(Delegate* delegate) = 0;

        // Returns the message loop for the thread on which this object
        // handles notifications, and also on which it must be destroyed.
        // Returns NULL if it does not matter.
        virtual const scoped_refptr<base::SingleThreadTaskRunner>&
        GetNotificationTaskRunner()
            = 0;

        // Returns the source of proxy settings.
        virtual ProxyConfigSource GetConfigSource() = 0;

        // These are all the values that can be fetched. We used to just use the
        // corresponding paths in gconf for these, but gconf is now obsolete and
        // in the future we'll be using mostly gsettings/kioslaverc so we
        // enumerate them instead to avoid unnecessary string operations.
        enum StringSetting {
            PROXY_MODE,
            PROXY_AUTOCONF_URL,
            PROXY_HTTP_HOST,
            PROXY_HTTPS_HOST,
            PROXY_FTP_HOST,
            PROXY_SOCKS_HOST,
        };
        enum BoolSetting {
            PROXY_USE_HTTP_PROXY,
            PROXY_USE_SAME_PROXY,
            PROXY_USE_AUTHENTICATION,
        };
        enum IntSetting {
            PROXY_HTTP_PORT,
            PROXY_HTTPS_PORT,
            PROXY_FTP_PORT,
            PROXY_SOCKS_PORT,
        };
        enum StringListSetting {
            PROXY_IGNORE_HOSTS,
        };

        // Given a PROXY_*_HOST value, return the corresponding PROXY_*_PORT value.
        static IntSetting HostSettingToPortSetting(StringSetting host)
        {
            switch (host) {
            case PROXY_HTTP_HOST:
                return PROXY_HTTP_PORT;
            case PROXY_HTTPS_HOST:
                return PROXY_HTTPS_PORT;
            case PROXY_FTP_HOST:
                return PROXY_FTP_PORT;
            case PROXY_SOCKS_HOST:
                return PROXY_SOCKS_PORT;
            default:
                NOTREACHED();
                return PROXY_HTTP_PORT; // Placate compiler.
            }
        }

        // Gets a string type value from the data source and stores it in
        // |*result|. Returns false if the key is unset or on error. Must only be
        // called after a successful call to Init(), and not after a failed call
        // to SetUpNotifications() or after calling Release().
        virtual bool GetString(StringSetting key, std::string* result) = 0;
        // Same thing for a bool typed value.
        virtual bool GetBool(BoolSetting key, bool* result) = 0;
        // Same for an int typed value.
        virtual bool GetInt(IntSetting key, int* result) = 0;
        // And for a string list.
        virtual bool GetStringList(StringListSetting key,
            std::vector<std::string>* result)
            = 0;

        // Returns true if the bypass list should be interpreted as a proxy
        // whitelist rather than blacklist. (This is KDE-specific.)
        virtual bool BypassListIsReversed() = 0;

        // Returns true if the bypass rules should be interpreted as
        // suffix-matching rules.
        virtual bool MatchHostsUsingSuffixMatching() = 0;

    private:
        DISALLOW_COPY_AND_ASSIGN(SettingGetter);
    };

    // ProxyConfigServiceLinux is created on the UI thread, and
    // SetUpAndFetchInitialConfig() is immediately called to synchronously
    // fetch the original configuration and set up change notifications on
    // the UI thread.
    //
    // Past that point, it is accessed periodically through the
    // ProxyConfigService interface (GetLatestProxyConfig, AddObserver,
    // RemoveObserver) from the IO thread.
    //
    // Setting change notification callbacks can occur at any time and are
    // run on either the UI thread (gconf/gsettings) or the file thread
    // (KDE). The new settings are fetched on that thread, and the resulting
    // proxy config is posted to the IO thread through
    // Delegate::SetNewProxyConfig(). We then notify observers on the IO
    // thread of the configuration change.
    //
    // ProxyConfigServiceLinux is deleted from the IO thread.
    //
    // The substance of the ProxyConfigServiceLinux implementation is
    // wrapped in the Delegate ref counted class. On deleting the
    // ProxyConfigServiceLinux, Delegate::OnDestroy() is posted to either
    // the UI thread (gconf/gsettings) or the file thread (KDE) where change
    // notifications will be safely stopped before releasing Delegate.

    class Delegate : public base::RefCountedThreadSafe<Delegate> {
    public:
        // Normal constructor.
        explicit Delegate(std::unique_ptr<base::Environment> env_var_getter);

        // Constructor for testing.
        Delegate(std::unique_ptr<base::Environment> env_var_getter,
            SettingGetter* setting_getter);

        // Synchronously obtains the proxy configuration. If gconf,
        // gsettings, or kioslaverc are used, also enables notifications for
        // setting changes. gconf/gsettings must only be accessed from the
        // thread running the default glib main loop, and so this method
        // must be called from the UI thread. The message loop for the IO
        // thread is specified so that notifications can post tasks to it
        // (and for assertions). The message loop for the file thread is
        // used to read any files needed to determine proxy settings.
        void SetUpAndFetchInitialConfig(
            const scoped_refptr<base::SingleThreadTaskRunner>& glib_task_runner,
            const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
            const scoped_refptr<base::SingleThreadTaskRunner>& file_task_runner);

        // Handler for setting change notifications: fetches a new proxy
        // configuration from settings, and if this config is different
        // than what we had before, posts a task to have it stored in
        // cached_config_.
        // Left public for simplicity.
        void OnCheckProxyConfigSettings();

        // Called from IO thread.
        void AddObserver(Observer* observer);
        void RemoveObserver(Observer* observer);
        ProxyConfigService::ConfigAvailability GetLatestProxyConfig(
            ProxyConfig* config);

        // Posts a call to OnDestroy() to the UI or FILE thread, depending on the
        // setting getter in use. Called from ProxyConfigServiceLinux's destructor.
        void PostDestroyTask();
        // Safely stops change notifications. Posted to either the UI or FILE
        // thread, depending on the setting getter in use.
        void OnDestroy();

    private:
        friend class base::RefCountedThreadSafe<Delegate>;

        ~Delegate();

        // Obtains an environment variable's value. Parses a proxy server
        // specification from it and puts it in result. Returns true if the
        // requested variable is defined and the value valid.
        bool GetProxyFromEnvVarForScheme(base::StringPiece variable,
            ProxyServer::Scheme scheme,
            ProxyServer* result_server);
        // As above but with scheme set to HTTP, for convenience.
        bool GetProxyFromEnvVar(base::StringPiece variable,
            ProxyServer* result_server);
        // Fills proxy config from environment variables. Returns true if
        // variables were found and the configuration is valid.
        bool GetConfigFromEnv(ProxyConfig* config);

        // Obtains host and port config settings and parses a proxy server
        // specification from it and puts it in result. Returns true if the
        // requested variable is defined and the value valid.
        bool GetProxyFromSettings(SettingGetter::StringSetting host_key,
            ProxyServer* result_server);
        // Fills proxy config from settings. Returns true if settings were found
        // and the configuration is valid.
        bool GetConfigFromSettings(ProxyConfig* config);

        // This method is posted from the UI thread to the IO thread to
        // carry the new config information.
        void SetNewProxyConfig(const ProxyConfig& new_config);

        // This method is run on the getter's notification thread.
        void SetUpNotifications();

        std::unique_ptr<base::Environment> env_var_getter_;
        std::unique_ptr<SettingGetter> setting_getter_;

        // Cached proxy configuration, to be returned by
        // GetLatestProxyConfig. Initially populated from the UI thread, but
        // afterwards only accessed from the IO thread.
        ProxyConfig cached_config_;

        // A copy kept on the UI thread of the last seen proxy config, so as
        // to avoid posting a call to SetNewProxyConfig when we get a
        // notification but the config has not actually changed.
        ProxyConfig reference_config_;

        // The task runner for the glib thread, aka main browser thread. This thread
        // is where we run the glib main loop (see
        // base/message_loop/message_pump_glib.h). It is the glib default loop in
        // the sense that it runs the glib default context: as in the context where
        // sources are added by g_timeout_add and g_idle_add, and returned by
        // g_main_context_default. gconf uses glib timeouts and idles and possibly
        // other callbacks that will all be dispatched on this thread. Since gconf
        // is not thread safe, any use of gconf must be done on the thread running
        // this loop.
        scoped_refptr<base::SingleThreadTaskRunner> glib_task_runner_;
        // Task runner for the IO thread. GetLatestProxyConfig() is called from
        // the thread running this loop.
        scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;

        base::ObserverList<Observer> observers_;

        DISALLOW_COPY_AND_ASSIGN(Delegate);
    };

    // Thin wrapper shell around Delegate.

    // Usual constructor
    ProxyConfigServiceLinux();

    // For testing: take alternate setting and env var getter implementations.
    explicit ProxyConfigServiceLinux(
        std::unique_ptr<base::Environment> env_var_getter);
    ProxyConfigServiceLinux(std::unique_ptr<base::Environment> env_var_getter,
        SettingGetter* setting_getter);

    ~ProxyConfigServiceLinux() override;

    void SetupAndFetchInitialConfig(
        const scoped_refptr<base::SingleThreadTaskRunner>& glib_task_runner,
        const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
        const scoped_refptr<base::SingleThreadTaskRunner>& file_task_runner)
    {
        delegate_->SetUpAndFetchInitialConfig(glib_task_runner,
            io_task_runner,
            file_task_runner);
    }
    void OnCheckProxyConfigSettings()
    {
        delegate_->OnCheckProxyConfigSettings();
    }

    // ProxyConfigService methods:
    // Called from IO thread.
    void AddObserver(Observer* observer) override;
    void RemoveObserver(Observer* observer) override;
    ProxyConfigService::ConfigAvailability GetLatestProxyConfig(
        ProxyConfig* config) override;

private:
    scoped_refptr<Delegate> delegate_;

    DISALLOW_COPY_AND_ASSIGN(ProxyConfigServiceLinux);
};

} // namespace net

#endif // NET_PROXY_PROXY_CONFIG_SERVICE_LINUX_H_
